Manufacture of food container and the like from aluminum foil or other thin metallic material



Aug. 18, 1964 1. EICHNER F. ETAL 3,144,974 MANUFACTURE OF FOOD CONTAINERAND THE LIKE FR OM ALUMINUM FOIL OR OTHER THIN METALLIC MATERIAL FiledJuly 10, 1959 2 Sheets-Sheet 1 THEIR ATTORNEYS Aug, 18, 1964 F. 1..EICHNER ETAL 3,144,974 MANUFACTURE OF FOOD CONTAINER AND THE LIKE FROMALUMINUM FOIL OR OTHER THIN METALLIC MATERIAL 2 Sheets-Sheet 2 FiledJuly 10, 1959 INVENTORS FRANK L. EICHNER MERRILL A. GROGEL WILLIAM-KORMAN WMQQWL THEIR ATTORNEY United States Patent f MANUFACTURE (BFFQUD UUNTAHNER AND THE LIKE FRilh l ALUMINUM b flifls 0R llllHEP-tTllllil i METAL'LHC MATERIAL Frank L. Eichner, Merrill A. Grogel, and ifilliam M. lion-man, Henrico County, Va, assignors to Reynolds MetalsCompany, Richmond, Va, a corporation of Delaware lFiled .luly 10, 1959,der. No. 826,191 4 Claims. (Cl. 229--3.5)

This invention relates to the manufacture of food containers fromaluminum or aluminum alloy foil or foillike sheets.

For the sake of brevity, the words thin sheet material are intended torefer to sheet material having an un embossed thickness in the order offrom 0.0015 to 0.006 inch in thickness, and the word aluminum as hereinused is intended to include not only aluminum alone but also the properaluminum alloys usable in this art.

Aluminum foil or foil-like material, as now manufactured, has beenprovided with a smooth shining and rcfiective surface. It has been theuniversal practice to retain this texture or surface in the manufactureof con tainers and receptacles in an effort to present attractiveness tosuch containers. Such practice has inherently in troduced certainunnoticed problems and disadvantages in the forming and drawing of thereceptacles, which this invention overcomes in a simple and emcientmanner.

Many of the unnoticed problems present in the prior practice are removedby the present invention with the retention of equal or superiorattractiveness in the product, and with the production of a superiorproduct.

According to this invention the thin sheet material preferably issimultaneously embossed and work hardened by an omni-directional or 360stretch embossing pattern which not only retains the attractiveness ofthe prior smooth shining foil, but also introduces further unexpectedresults with the elimination of previously unnoticed problems anddisadvantages inherently present in such previous practice.

The omni-directional stretch embossing pattern now preferred has aplurality of closely formed, irregularly curved, narrow or hair-likeundulations adjacent each other, some of which are irregular C'shapedpatterns, and in which the prevailing length of the undulations is inthe order of from V to an inch in length, and the height is in the orderof from 0.001 to 0.005 inch.

Containers manufactured from aluminum thin sheet material having theomni-directional stretch embossing pattern of this invention aresurprisingly attractive, and eliminate many problems and disadvantageswhich have been previously unnoticed.

For example, die drawing operations are greatly improved. The smoothshining thin sheet material previously used is incompressible and variesas much as in thickness throughout a run of material. Drawing dies forthin sheet material of this kind are oftentimes provided withsurrounding pressing plates which must maintain an evenly distributedfrictional drag on the sheet ma terial as the drawing dies pull thematerial into the desired container form. The thin sheet material ispulled, rather than drawn, as the dies move toward each other,particularly in the formation of slanting wall containers. Since theprior smooth thin sheet material is smooth and incompressible by the diesurrounding pressure plates, the 10% thickness variation in the sheetmaterial and local variations within the sheet material can cause thepressure plates to produce an uneven frictional drag around the dieswith consequent uneven pull and formation of the container. On the otherhand the embossed thin sheet material, as used in this invention, has aspongy reaction (due to the foil-like thinness of the sheet) as itpasses ildl i ifl'id Patented Aug. lib, lbdd through the pressingplates, which enables the pressing plates to produce an evenlydistributed frictional drag around the dies to produce a superiorcontainer.

During many of the forming and drawing operations of the containersherein described, bends and corners are produced which require the thinsheet material locally to elongate differentially with respect to thesurrounding sheet material. The thin sheet material of the previouspractice is very limited in its capacity locally so to elongatedilferentially because of 'its smooth and thin construction. Thisprovides only a limited amount of material in the thin sheet to producethis local elongation. With the embossed sheet used in this invention,the elongation is predistributed in a manner so there is always at leastone, or more, undulation present which provides sufficient elongation bythe straightening of the undulation rather than by an undue localstretching of the thin sheet of the prior practice, which previously waslikely to produce a rupture or weak wall. Hence the forming or drawingprocedures are greatly improved by this invention.

The temper and hardness necessary for successful forming and drawingoperations are more easily, effectively and cheaply obtained by thepractice of this invention. The methods of hardening the thin smoothsheet material of prior practice have been expensive or unsatisfactoryas compared to the practice of this invention. For example, the priorsmooth thin aluminum sheet of prior practice has been work hardened bypassing the material through a selected number of rolls, then has beenannealed substantially to dead softness, and then again passed through anumber of rolls presumably to produce the desired thickness andhardness, which desired hardness usually is a fraction of full hardness,which for example, is half hardness. However, thin aluminum sheet sowork hardened has very poor stretch characteristics, and hence is poorforming or drawing material. Another more satisfactory, but morecritical and expensive, prior method of tempering has been to pass thematerial through a number of rolls to produce the desired thickness andusually a full hardness, and thereafter to soften the material to thedesired fractional hardness in an annealing furnace. However this is avery critical and relatively expensive procedure, as the annealingfurnace treatment requires a very narrow and critical temperature bandto produce the desired fractional hardness. According to this invention,the desired fractional hardness is obtained by smooth rolling to anintermediate thickness and annealing substantially to dead softness, orany easily controlled softness, and then usually by smooth rolling tothe desired thickness, and by embossing in rolls to produce the desiredfractional hardness. Such work hardened sheet has good stretchcharacteristics due to the embossing pattern which is superior to theprior first de scribed rolling, annealing and rolling process, and isalso much cheaper and less critical than the second described prior,more expensive process of rolling to full hardness and fractionalannealing above described.

Lubrication during the forming or drawing operations is improved by thepractice of this invention. The lubricant which is usually provided forthese operations is more etllciently carried to the operating Zone ofthe forming or drawing press, since the lubricant is efficiently carriedin the valleys or interspaces of the undulations without the loss oflubricant in transportation as is frequent in the prior smooth sheetconstruction.

The smooth shining surfaces of the prior receptacles, which so netirnespresent an attractive appearance, actually often accentuate surfaceimperfections or misalignments, because the reflections from thesesmooth surfaces cause the imperfections and misalignments to stand outor be magnified in an unattractive manner. This is avoided by thepractice of this invention.

Thinner gauge sheet embossed material may be used by this invention toproduce the rigidity of thicker smooth sheet material. This isparticularly true where the containers have relatively large fiatsurfaces. For example, in horizontally rectangular receptacles withgently sloping side walls, it is possible to use embossed sheet materialwhich is 0.0005 to 0.001 inch thinner to produce the same rigidity ofthicker smooth sheet material. Also the same press and die can operateon 0.0005 to 0.001 inch thinner embossed material. This added rigidityof the embossed material permits a saving in cost by the use of thinnermaterial, as well as by the cheaper and more effective temperingprocedure above described.

Containers manufactured according to this invention are superior inquality, are pleasing in appearance, and are cheaper in cost.

Hence it is an object of this invention to provide improved methods andproducts having one or more of the above improved characteristics.

Further objects and advantages will become apparent as the descriptionproceeds with reference to the accompanying drawings, in which:

FIGURE 1 is an enlarged surface view of an embossed thin sheet ofaluminum or similar metal made according to tins invention, which isadjacent to an enlarged measuring scale.

FIGURE 2 is a top view of a rectangular cover and receptacle which maybe made of embossed thin metal sheet according to this invention.

FIGURE 3 is a vertical view partly in elevation and partly in section ofthe cover over receptacle of FIGURE 2, spread vertically apart and takenalong the line 3-3 of FIGURE 2.

FIGURE 4 is a, vertical view similar to FIGURE 3 taken along the line 44of FIGURE 2.

FIGURE 5 is a top view of a circular, tapered side wall receptacle whichmay be made according to this invention.

FIGURE 6 is a cross-section taken along the line 6-6 of FIGURE 5.

FIGURE 7 is a top view of another receptacle which may be made accordingto this invention.

FIGURE 8 is a cross section taken along the line 8-0 or" FIGURE 7.

FIGURE 9 is a cross section taken along the line 9-9 of FIGURE 7.

FIGURE 10 is a diagrammatic cross-section of a typical press forproducing some of the receptacles made according to the invention.

FIGURE 11 is a further enlargement of the embossing pattern shown inFIGURE 1.

FIGURE 12 is a cross-section taken substantially along the line 12-12 ofFIGURE 11, showing a cross-section produced by a single embossing rolland cooperating smooth flexible roll.

FIGURE 13 is a diagrammatic view showing the simultaneous embossing andwork hardening of thin sheet material according to this invention.

FIGURE 14 is a diagrammatic view somewhat similar to FIGURE 12, showinga cross-section produced by a pair of matching embossing rolls, each ofwhich has hills and valleys.

Referring first to FIGURE 1, a metallic thin sheet 20, such as analuminum containing sheet, is in the order of from 0.0015 to 0.006 inchin thickness. Preferably it has been simultaneously embossed and workhardened to the desired hardness with an omni-directional stressembossing pattern having, for example, a plurality of closely formed,irregularly curved, narrow or hair-like undulations 22 adjacent eachother, some of said undulations forming irregular (J-shaped patterns, asindicated, for example, at 23. The prevailing length of said undulationsis in the order of from 1 to inch in length. These undulations have aheight transverse to the sheet in the order of from 0.001 to 0.005 inchand preferably give an apparent thickness as measured by a standardmicrometer of from to 200% of the thickness of the sheet. This apparentthickness is the perpendicular distance from the highest point or creston one side of the sheet to the highest point or crest on the oppositeside of the sheet. The embossing pattern has not been illustratedthroughout the area of FIGURE 1, but it is understood that the embossingpattern is more or less uniform and does extend throughout the area,except as hereinafter specifically described. Other equivalent embossingpatterns may also be used.

FIGURE 1 also includes an enlargement of a measuring scale 21 which hasbeen enlarged exactly to the same extent as the enlargement of sheet 20.In the original scale, before enlargement, the distance (A) was A inchlong, distance (B) was /s inch long, distance (C) was A inch long, anddistance (D) was /2 inch long.

The simultaneous embossing and final work hardening of the sheet 20 tothe desired hardness may be accomplished as diagrammatically indicatedin FIGURE 13. A thick sheet 24, of dead softness, for example, may bedrawn and elongated through a number of rolls 26 so the sheet, at 20, isat a substantial or full hardness and the thickness has been reduced toany desired degree. The sheet is then passed through the annealingfurnace 30 and emerges at 32 in a dead soft condition, or in any easilycontrolled substantially soft condition. If desired, the sheet may thenpass through one or more smooth rolls 34-, further to decrease thethickness and partially to increase the hardness. Under certainconditions, the rolling by rolls 34 may be omitted. Thereafter the sheetis passed through the embossing rolls 36, or through an embossing rolland a smooth resilient roll,

simultaneously to emboss and work harden the sheet to the desiredhardness with the omni-directional stretch embossing pattern shown inFIGURE 1. The desired final hardness is controlled, in part, by thepressure applied at the rolls as. The sheet emerges from the rolls 36,as indicated at 2-0, in the embossed condition of FIG- URE 1, and iswork hardened to the desired degree. Eventually, it is formed or drawnby a suitable apparatus or press, as diagrammatically indicated at 38.If desired, the sheet 20, in FIGURE 13, may be rolled up and stored forfuture use in the apparatus 38, or for future use in variously differentmachines 38, as may be desired.

FIGURE 11 shows a further enlargement of the embossing pattern shown inFIGURE 1, which is intended merely to indicate a typical condition. Thedistance between the particular undulations 22 illustrated in FIG- URE11 from crest 22A to crest 22A, or from crest to valley variesthroughout the pattern of sheet 20 as shown in FIGURE 1, and may bevariously determined in FIG- URE 1 by comparison with the measuringscale distances (A), (B), (C), and (D). The undulations may be all onone side of the sheet, as indicated in FIGURE 12, or they may be on bothsides of the sheet, as indicated in the FIGURE 14. The sheet of FIGURE12 is produced by a single embossing roll cooperating with a smoothflexible roll. The sheet of FIGURE 14 is produced by a pair of embossingrolls, each having hills and valleys.

FIGURES 2, 3 and 4 show a substantially rectangular container 40 whichmay be made of embossed thin sheet material, such as shown in FIGURE 1,and which may be used with or without the matching cover 42 likewisemade of embossed thin sheet material of this invention. In use the cover42 is moved down from the spaced position shown in FIGURES 3 and 4 sothe upper edges 44 and 4-6 respectively of the side walls 40 and 50 arereceived within the inside of the inverted V edges 52 and 54 of thecover 3-2. When the cover 42 and the receptacle 40 are so assembledtogether, the edges 44, 46, 52, and 54 are crimped together to secureand/or seal the receptacle and cover together. The container orreceptacle 40 has a flat rectangular bottom 56, and opposed pairs offiat side walls 48 and 50, one of the pairs of side walls, such as 50,having folded corners 58. All of said side walls 43 and 50 havereversely directed flaps 60 and 62 respectively which are rounded attheir ends, as indicated at 64.

The covers 42 have a rectangular lower deck 66 from which the invertedgrooves 52 and 54 rise. The grooves 54 extend downwardly to form tabs68, While the grooves 52 extend downwardly to form a shorter tab 70 andto form another tab 72 which may be longer than the tab 70, and whichmay be a pull tab. The tab 70 may be substantially of the same length asthe tabs 68.

Containers of the character disclosed in FIGURES 2, 3 and 4, without theembossed pattern, have been extensively used. These horizontallyrectangular receptacles, with their gently sloping side walls, areimproved materially by the use of the omni-directional stretch embossingpattern in the thin sheet material used to form such receptacles andcovers. The embossed sheet material may be as much as 0.0005 to 0.001inch thinner material to produce the same rigidity of the thicker smoothsheet material. Also, smooth foil aluminum containers and covers of thistype have not heretofore been satisfactorily formed with foil which isthinner than about 0.004 inch, whereas containers with foil embossed asherein disclosed may be formed with omni-directionally embossed foil ofaluminum which is 0.003 inch in thickness, and such embossed containersand covers have substantially the same rigidity as the smooth foilcontainers of 0.004 inch in thickness The same relative superiority ofthe embossed thin sheet containers, of thicker gauge, exists oversimilarly corresponding smooth containers.

The forming process and apparatus to produce the covers and containersof FIGURES 2, 3, and 4 are much more effective when the embossed thinsheet material of this invention is used in forming the containers andcovers.

The baking and other cooking characteristics of containers are improvedby the use of omni-directionally embossed thin sheet material, inaccordance with this invention. For example, referring to the circularpie plate shown on FIGURES 5 and 6, may be made from the embossed sheetmaterial as described in connection with FIGURE 1. The pie plate 76 mayhave a substantially fiat circular bottom 78 with or without thecircular grooves 80 and 82 and the radial grooves $4. These grooves 80,82, and 84 may be omitted, particularly in pie pans later to bedescribed, and in similar circular receptacles of smaller diameter.

The container 76 has a circumferentially disposed side wall 86, saidside wall being outwardly and upwardly flared and having a bead 88 and aflange 90 along its upper edge.

The baking and other cooking characteristics of the container 76, andsimilar containers, are greatly improved by use of the embossed sheetmaterial by reason of the increased area which is exposed for heatabsorption. In addition, the release characteristics of baked or othercooked products are enhanced by the embossing pattern. For example, theunbaked dough which is to produce the baked or cooked product does notgo into the valleys of the embossment because of its putty-like nature.Consequently, when carmelization takes place, because of the sugarcontent of the dough, the caramel substance adheres only to the tops ofthe hills of the embossment, which hills are a minor part of the entiresurface involved. The baked product can be more easily removed from theslightly adhering caramel at the tops of the hills as compared to thecomplete adherence in the case of smooth foil where the carmelizationadheres to the entire surface because such entire smooth surface isavailable for the adherence of unbaked dough.

The pie plate 76 shown in FIGURES 5 and 6 may also be made, according tothis invention, with the embossing pattern applied substantially only tothe bottom 78 and With the remainder of the sheet, which forms the pieplate, made of smooth sheet material. The bottom grooves 80, 82 and 84may be used or omitted in this embodiment. If they are omitted, thebottom 7 8 has sufiicient rigidity imparted thereto by the embossingpattern.

The pie plate with the bottom only having the embossed pattern has anadvantage in that the baking characteristics heretofore described areenhanced by the embossing pattern on the bottom. The side Wall 86 hasmany wrinkles formed in it during the drawing operation which impartgood baking characteristics to the side wall whether the metal sheet isembossed or not in the side wall area. The head 88 and flange 90likewise are eificient to a sufficient degree, whether the metal sheetis embossed or not. However, the bead 88 is believed to be slightlystronger when the metal sheet is unembossed. Consequently the pie plate76 of this embodiment has its bottom area 78 increased in strength andin baking qualities by the embossed pattern, while the side wall 86,bead 88, and flange 90 are retained in their original satisfactoryconditions produced by the unembossed portion of the metal sheet. Hencethe pie plate of this embodiment is superior to the prior unembossed pieplates. The embossing pattern of this embodiment may be formed in themetal sheet at the area which is to form the bottom prior to the drawingprocess, or the embossing pattern may be formed by the drawing pressbetween the punch and die members. When a plurality of plates of thisembodiment are to be made from a strip of sheet material, such strip maybe embossed at proper intervals and in proper shapes to form the bottomof the plates as the plates are blanked out of the strip, or the stripmay be maintained smooth throughout and the bottom embossment may bemade by the drawing press, .as desired.

Another type of container which is improved by the use ofomni-directionally embossed foil or thin sheet material, in accordancewith this invention, is illustrated in FIGURES 7, 8 and 9. The container92 shown in FIG- URES 7, 8 and 9 is of the character used for frozendinners and the like. Ordinarily it has a substantially rectangularshape with upwardly and outwardly directed side walls 94. It has asubstantially fiat bottom 96, which is substantially flat except for theintegral inverted V-shaped dividers 98 and 100 which extend upwardly andintegrally from the bottom 96. The upwardly directed sides 94 have beads102 and flanges 104. The corners are rounded at 106.

The container 92 has three compartments 108, 110, and 112 for thereception of various parts of the dinner. There are several sharpcorners, particularly at 114 and 116, as well as the square corners at106 which require the sheet material to stretch considerably during thedrawing operation.

The tray FIGURES 7, 8, and 9 is greatly improved by the use of theembossed thin sheet 20, in accordance with this invention, because thestretching qualities of the embossed foil or sheet permit the materialto stretch the required amount for the sharp corners at 114 and 116, thesquare corners at 106, and any other places where undue stretching isrequired.

The forming or drawing qualities of the embossed foil or sheet make thepractice of this invention particularly advantageous in connection withthe receptacles heretofore described. The stretching and drawingqualities of the embossed sheet, due to the embossing pattern, and thespongy quality of the sheet, due to the thinness of the sheet, permitthe material to be drawn or formed with greater ease than is the casewith smooth sheets.

For example, in connection with the drawing operations for thereceptacles of FIGURES 5 to 9 inclusive, the embossed thin sheets may bemore uniformly drawn, as will become apparent with reference to FIGURE10 which shows a typical die press.

In FIGURE 10, the die press may include a punch member 122 and a diemember 124. These members are movable relatively to each other. Inthe'case illustrated, the die member 124 is moved downwardly by anysuitable means diagrammatically indicated by the spring construction126. The die member has a leading mouth edge 128 and the punch memberhas a leading face 130 with a leading edge 132. The leading mouth 128and the leading edge 132 pull the thin sheet material between thecombined upper pressure plate construction 134 and 136 and the combinedlower pressure plate construction 138 and 140. The combined pressureplate construction 134, 136, 138, and 140 provides a frictional slidingresistance to the sheet material as the sheet material is drawn into theconical shape of the die press cavity.

Aluminum thin sheet material of the thickness herein described has a 10%variation in thickness and such variation causes the pressure plateconstruction to produce uneven frictional drag around the die members122 and 124 since thin smooth sheet material is uncompressible by thepressure plate construction. On the other hand, the embossed aluminumthin sheet material, as used in this invention, has a spongy reaction asit passes through the combined pressure plate constructions 134, 136,138, and 140, which enable these constructions to produce an evenlydistributed frictional drag around the die members 124 and 122.

During the drawing operation, many bends and stretching points areencountered for which the smooth thin sheet material does not havesufficient stretch characteristics. This is particularly true at suchcorners as 106, 114, and 116 of FIGURES 8, 9, and 10. The stretchingqualities of the embossed undulations predistributes the stretchingqualities of the embossed sheets so that there is always at least onestretchable undulation near the stretch points of such corners or edges.

Other members diagrammatically indicated in FIGURE 10 include yieldablemeans such as spring constructions 142 to maintain the member 140 upwardand to yield to the downward movement of the member 136 above, which ismoved down by the diagrammatic spring construction 143. The member 140has an inward flange 144 which passes around the ring 146, and permitsthe ring 146 to stop the member 138 before the bottom of the stroke isreached. The members 134 and 138 produce the flange 90 or the flange 104of FIGURES to 9. The bead 88 or the bead 102 are formed by the furtherdownward movement of the members 136 and 140 which form the bead on thereturn stroke by operation of the ring cavities 148 and 150 in a mannerwell known in the art. The blank cutting and pressure ring 152 is moveddownwardly by any resilient means such as spring 154 against thestationary cutting and pressure ring 156 which is supported bystationary guide ring 158. The rings 152 and 156 out a circular blankfrom the strip of material being fed through the press as the members136 and 140 move downwardly. A knockout member 160 is operated by theplunger 162 at the proper time to release the receptacle which has beendrawn.

The spring constructions diagrammatically shown at 126, 142, 143 and 154may include well known proper reciprocatable plungers, platforms, etc.,which insure proper operation of the elements moved thereby.

From the foregoing it will be evident that the spongy character of therelatively thin embossed sheet permits proper cooperation with thecombined pressure plate members 134, 136, 138, and 140 to insure a moreeven inward feeding of the thin sheet into the drawing cavity and topermit the necessary elongation of the material as it passes through thevarious bending points in a manner superior to the smooth foilheretofore used.

Folded foil containers of the square type herein disclosed in FIGURES 2,3 and 4, have relatively sharp, square corners. In forming these trays,elements of the blank at the corners are folded and pressed flat. Forstrength and rigidity the folded tray requires that the stock be in ahardened temper, i.e., to full hard temper.

It has been found that the strain imposed in the folding operationexceeds the elongation properties of the plain, smooth foil stock ingauges lighter than .004" and result in cracking and breaking at thefolded edges. In effect, the folding operation is a bend of the stockaround a Zero thickness inner radius and a thickness outer radius equalto the thickness of the sheet material. Practical experience has shownthat the minimum outer radius for the 180 bend in the tempered foilwithout cracking is .004"; thus .004" has been established as theminimum plain smooth stock gauge.

In attempting to establish whether embossing before forming would enablethe square trays to be produced from a lighter gauge of stock, embossedstock of this invention was used. The stock having the pattern of thisinvention produced quality trays. Foil gauge before embossing was .003".Micrometer measurements of the embossed stock gave an apparent thicknessof .005". This represents a measurement between the peaks on one side tothe peaks on the other side produced by embossing.

Examination of the square type trays of FIGURES 2, 3 and 4 produced fromthe .003" embossed stock leads to the conclusion that the successful useof the light gauge stock is due to two characteristics imparted byembossing:

(1) In the forming operation the rough embossed surfaces are notflattened at the folds. Thus the outside radius on a 180 bend is equalto the measured thickness of the embossed metal rather than to thethickness of the plain smooth stock before embossing. As pointed outabove, in the case of embossed aluminum sheet or foil of this invention,this apparent thickness is .005" rather than the .003" thickness of thefoil before embossing. This .005" outer radius at the flat folds causesno difficulty with cracking or breaking at the folded edges.

(2) In embossing according to this invention, the pattern is imparted bybending and forming with substantially no reduction in metal thickness.This results in a slight shrinkage of lineal dimensions of plain foilwhen embossed. When embossed foil is subjected to'tensile strain, thefirst etfect is the removal of the embossed pattern before any reductionin basic metal thickness takes place. In forming containers certainsmall areas of the blank are highly strained. In these areas the stockrequired for forming the required contour is obtained by flattening ofthe embossed pattern rather than solely by a reduction in metalthickness such as would occur if plain foil was used. On the light foilor sheet gauges herein specified and used for containers, anyappreciable reduction in basic metal thickness at the highly stressedareas frequently results in fractures at these points.

The practice of this invention produces a superior product, at reducedcost, and in most cases retains the rigidity on thinner embossedmaterial than was maintained by a thicker smooth material. It permitsthe use of about 0.001 inch thinner sheet material, such as 0.003 inchinstead of 0.004 inch with the same or superior results. The practice ofthe invention also reduces corner crack during the formation of thecontainers, and improves the baking and cooking characteristics of thecontainers. Added elongation is provided in the material, and the temperand hardness of the material are easily and more cheaply controlled thanis the case with smooth material. Lubricant is carried more efficientlyin the valleys of the embossed material to the drawing presses and otherforming apparatus. Surface imperfections in the material are hidden,defaced, or repaired and reflections on imperfections do not stand outas is the case with smooth material. Improved forming and drawingcharacteristics of the thin sheet are enhanced. And a pleasingappearance is provided.

While the form of the invention now preferred has been disclosed, inaccordance with the requirements of the statutes, other forms may beused, all coming within the scope of the claims which follow.

What is claimed is:

1. The method of manufacturing a food container and the like from analuminum containing thin sheet of from 0.0015 to 0.006 inch in thicknessand having at least one cup-shaped compartment formed therein anddefined by drawing critical bends in said sheet to produce integralcontinuous side walls of said compartment which comprises:simultaneously embossing and work hardening said sheet to the desiredhardness with an omni-directional stretch embossing pattern having aplurality of closely formed narrow undulations adjacent each other, saidundulations causing said sheet to have an apparent thickness in theorder of 130% to 200% of the thickness of the unembossed sheet; andforming said sheet into the form of said container by stretching saidsheet at the critical bends of said container without substantiallychanging the actual cross-sectional thickness of said sheet.

2. A container formed from an aluminum containing thin sheet of from0.0015 to 0.006 inch in thickness and having at least one cup-shapedcompartment formed therein and defined by drawing critical bends in saidsheet to produce integral continuous side walls of said compartment,said sheet being embossed and work hardened to the desired degree withan omni-directional stretch embossing pattern including a plurality ofclosely formed, narrow undulations adjacent each other, said undulationscausing said sheet to have an apparent thickness in the order of 130% to200% of the thickness of the unembossed sheet said sheet being stretchedat the critical bends of said container without substantial change inthe actual cross-sectional thickness of said sheet.

3. A container made from a metallic thin sheet of from 0.0015 to 0.006inch in thickness and having at least one cup-shaped compartment formedtherein and defined by drawing critical bends in said sheet to produceintegral continuous side walls of said compartment, said sheet beingembossed and work hardened to the desired degree with anomni-directional stretch embossing pattern including a plurality ofclosely formed, irregularly curved, hairlike undulations adjacent eachother, the prevailing length of said undulations being in the order offrom to in length, said undulations causing said sheet to have anapparent thickness in the order of to 200% of the thickness of theunembossed sheet, said sheet being stretched at the critical bends ofsaid container without substantial change in the actual cross-sectionalthickness of said sheet.

4. The method of manufacturing a container from an aluminum containingthin sheet in the order of from 0.0015 to 0.006 inch in thickness andhaving at least one cup-shaped compartment formed therein and defined bydrawing critical bends in said sheet to produce integral continuous sidewalls of said compartment which comprises: embossing said sheet with anomni-directional stretch embossing pattern including a plurality ofclosely formed undulations adjacent each other, said undulations causingsaid sheet to have an apparent thickness in the order of 130% to 200% ofthe thickness of the unernbossed sheet; and forming said sheet int oform of said container by stretching said sheet at the critical pointsof said container without substantially changing the actualcross-sectional thickness of said sheet.

References Cited in the file of this patent UNITED STATES PATENTS319,306 Palmer June 2, 1885 499,359 Hall June 13, 1893 1,940,664 CoyleDec. 26, 1933 2,174,425 Schlumbohm Sept. 6, 1939 2,257,468 Langel Sept.30, 1941 2,274,835 Koch Mar. 3, 1942 2,312,749 Bullock Mar. 2, 19432,629,534 Reynolds Feb. 24, 1953 2,669,914 Swaine Feb. 23, 19542,775,383 Kollman et al. Dec. 25, 1956 2,802,411 Riener Aug. 13, 19572,878,128 Jorgenson Mar. 17, 1959 2,899,922 Wheeler Aug. 18, 1959

2. A CONTAINER FORMED FROM AN ALUMINUM CONTAINING THIN SHEET OF FROM0.0015 TO 0.006 INCH IN THICKNESS AND HAVING AT LEAST ONE CUP-SHAPEDCOMPARTMENT FORMED THEREIN AND DEFINED BY DRAWING CRITICAL BENDS IN SAIDSHEET TO PRODUCE INTGEGRAL CONTINUOUS SIDE WALLS OF SAID COMPARTMENT,SAID SHEET BEING EMBOSSED AND WORK HARDENED TO THE DESIRED DEGREE WITHAN OMMI-DIRECTIONAL STRETCH EMBOSSING PATTERN INCLUDING A PLURALITY OFCLOSELY FORMED, NARROW UNDULATIONS ADJACENT EACH OTHER, SAID UNDULATIONSCAUSING SAID SHEET TO HAVE AN APPARENT THICKNESS IN THE ORDER OF 130% TO200% OF THE THICKNESS OF THE UNEMBOSSED SHEET SAID SHEET BEING STRETCHEDAT THE CRITICAL BENDS OF SAID CONTAINER WITHOUT SUBSTANTIAL CHANGE INTHE ACTUAL CROSS-SECTIONAL THICKNESS OF SAID SHEET.